## Dr Tom Billam

MSci (Durham), PhD (Durham)

Postdoctoral Research Fellow

thomas.billam@otago.ac.nz

Room 410

ph +64 3 4794006

fax +64 3 4790964

## Research areas

My principal research interests are the non-equilibrium dynamics of ultracold Bose gases. In particular I am interested in:

**Quantum vortex dynamics and two-dimensional quantum turbulence**

This area has been my main focus at Otago, where I have worked on schemes for vortex injection in BECs, and on methods of analysis for vortex dynamics, with

Ashton Bradley and others.

**Non-equilibrium BEC dynamics in the presence of significant quantum depletion**

In this area I have a long-standing collaboration with

Simon Gardiner developing and implementing number-conserving techniques for coupled condensate - non-condensate dynamics at finite temperatures. A focus for our work to date has been quantum chaos and quantum resonances in driven BEC systems.

**Bright solitary matter-waves: dynamics and applications to interferometry**

I have worked on a variety of topics related to bright solitons in attractively-interacting BECs, including proposals for interferometric schemes exploiting their non-dispersive behaviour. More recently, I have worked with

Christoph Weiss and others studying the quantum behaviour of bright solitons for small atom numbers, and provided numerical modelling for the successful

^{85}Rb bright soliton experiment of

Simon Cornish.

## Publications

Google Scholar page

Full arXiv preprint listing

*Signatures of Coherent Vortex Structures in a Disordered 2D Quantum Fluid*

M. T. Reeves, T. P. Billam, B. P. Anderson, and A. S. Bradley

Physical Review A **89**, 053631 (2014)

*Onsager-Kraichnan Condensation in Decaying Two-Dimensional Quantum Turbulence*

T. P. Billam, M. T. Reeves, B. P. Anderson, and A. S. Bradley

Physical Review Letters **112**, 145301 (2014)

*Generating Mesoscopic Bell States via Collisions of Distinguishable Quantum Bright Solitons*

B. Gertjerenken, T. P. Billam, C. L. Blackley, C. R. Le Sueur, L. Khaykovich, S. L. Cornish, and C. Weiss

Physical Review Letters **111**, 100406 (2013)

*Controlled formation and reflection of a bright solitary matter-wave*

A. L. Marchant, T. P. Billam, T. P. Wiles, M. M. H. Yu, S. A. Gardiner, and S. L. Cornish

Nature Communications **4**, 1865 (2013)

*Second-order number-conserving description of nonequilibrium dynamics in finite-temperature Bose-Einstein condensates*

T. P. Billam, P. Mason, and S. A. Gardiner

Physical Review A **87**, 033628 (2013)

*Inverse Energy Cascade in Forced 2D Quantum Turbulence*

M. T. Reeves, T. P. Billam, B. P. Anderson, and A. S. Bradley

Physical Review Letters **110**, 104501 (2013)

*Equilibrium solutions for immiscible two-species Bose-Einstein condensates in perturbed harmonic traps*

R. W. Pattinson, T. P. Billam, S. A. Gardiner, D. J. McCarron, H. W. Cho, S. L. Cornish, N. G. Parker, and N. P. Proukakis

Physical Review A **87**,013625 (2013)

*Scattering bright solitons: Quantum versus mean-field behavior*

B. Gertjerenken, T. P. Billam, L. Khaykovich, and C. Weiss

Physical Review A **86**,033608 (2012)

*Bright matter-wave soliton collisions at narrow barriers*

J. L. Helm, T. P. Billam, and S. A. Gardiner

Physical Review A **85**, 053621 (2012)

*Coherence and instability in a driven Bose-Einstein condensate: a fully dynamical number-conserving approach*

T. P. Billam and S. A. Gardiner

New Journal of Physics **14**, 013038 (2012)

*Variational determination of approximate bright matter-wave soliton solutions in anisotropic traps*

T. P. Billam, S. A. Wrathmall, and S. A. Gardiner

Physical Review A **85**, 013627 (2012)

*Realizing bright-matter-wave-soliton collisions with controlled relative phase*

T. P. Billam, S. L. Cornish, and S. A. Gardiner

Physical Review A **83**, 041602(R) (2011)

*Quantum resonances in an atom-optical δ-kicked harmonic oscillator*

T. P. Billam and S. A. Gardiner

Physical Review A **80**, 023414 (2009)

## Book Chapters

*Number-Conserving Approaches for Atomic Bose-Einstein Condensates: An Overview*

S. A. Gardiner and T. P. Billam

In *Quantum Gases: Finite Temperature and Non-equilibrium Dynamics*, edited by N. P. Proukakis, S. A. Gardiner, M. Davis, and M. Szymanska (Imperial College Press, London, 2013), Chap. 8 (arXiv:1207.6382)

*Bright Solitary Matter Waves: Formation, Stability and Interactions*

T. P. Billam, A. L. Marchant, S. L. Cornish, S. A. Gardiner, and N. G. Parker

In *Spontaneous Symmetry Breaking, Self-trapping, and Josephson Oscillations*, edited by B. Malomed (Progress in Optical Science and Photonics, Springer, Berlin, 2012) (arXiv:1209.0560)

## Conference Proceedings

*Entangling two distinguishable quantum bright solitons via collisions*

T. P. Billam, C. L. Blackley, B. Gertjerenken, S. L. Cornish, and C. Weiss

J. Phys.: Conference Series **497**, 012033 (2014)